AIDS epidemic update 2007

ABSTRACT

In 2007, advances in the methodology of estimations of HIV epidemics applied to an expanded range of country data have resulted in substantial changes in estimates of numbers of persons living with HIV worldwide. Because estimates of new HIV infections and HIV-associated deaths are derived through mathematical models applied to HIV prevalence estimates, new estimates of HIV incidence and mortality in 2007 also differ substantially from earlier assessments. The AIDS epidemic update reports on the latest developments in the global AIDS epidemic and has been published annually since 1998. The 2007 edition provides the most recent estimates of the epidemic’s scope and human toll and explores new trends in the epidemic’s evolution. The major elements of methodological improvements in 2007 included greater understanding of HIV epidemiology through population-based surveys, extension of sentinel surveillance to more sites in relevant countries, and adjustments to mathematical models because of better understanding of the natural history of untreated HIV infection in low- and middle- income countries. These adjustments to the methodology used are explained in more detail in the box “New data lead to changes in assumptions and improved estimates.”